pnfsblock: cleanup bl_mark_sectors_init

It does not need to manipulate on partial initialized blocks.
Writeback code takes care of it.

Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
3 files changed